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Phil Starr

1x12" Cab Design Diary

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Rehearsal went well, the cab sounded great. I’m amazed really at how good it does sound. I got a metal grill made too so it looks really professional!

Although at 8ohms it makes my amp work too hard and I’m pretty sure it won’t cut it for a gig. So I’m going to make another one! I sent off the dimensions to a number of online timber cutting services but can’t as yet find anyone prepared to cut the speaker hole. I’m pretty sure I can manage the holes for the ports. Does anyone know where I might get the speaker hole cut for a reasonable price as I don’t have the skill or the necessary equipment to do this?

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I'm pleased you liked the sound. I've been happy with one for gigs in small to medium venues but two do give you a lot more authority. You can cut the port holes with a holesaw which will cost you about £10. Most joiners or kitchen fitters would be able to cut you a hole for the speaker or you can do it with a cheap jigsaw. It's a shame I didn't see this earlier as I was up in Bristol visiting my daughter and could have cut something for you.

I don't know if these people might cut something for you, worth a ring? http://www.avonply.co.uk/Default.aspx

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I know it was mentioned long ago in this thread but curiosity has me asking.

Since there aren't many commercial cabs that tune to 30hz  ( if any ? ), how to 5 strings players cope with that B string, which is what - 31hz - ish ?

 

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8 hours ago, fleabag said:

I know it was mentioned long ago in this thread but curiosity has me asking.

Since there aren't many commercial cabs that tune to 30hz  ( if any ? ), how to 5 strings players cope with that B string, which is what - 31hz - ish ?

 

FWIW, I use a 4 string tuned Bb, EB, Ab, C# on some songs and my pair of these cabs don't struggle at all. They are quite bassy anyway. 

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11 hours ago, fleabag said:

I know it was mentioned long ago in this thread but curiosity has me asking.

Since there aren't many commercial cabs that tune to 30hz  ( if any ? ), how to 5 strings players cope with that B string, which is what - 31hz - ish ?

 

because there is very little fundamental in what a bass puts out. The pickups are in completely the wrong place to pick up the fundamental, they'd need to be under the 12th fret to do that. Our ears are incredibly insensitive to sound below 100Hz anyway so we don't really miss the little bit of bass anyway. Well, not very much. most of what we hear as bass  is the second harmonic (double the frequency of the fundamental) so 82Hz for a bottom E and up around 100Hz for most of what we play, 80-160 maybe.

Bassiness is about the mix of harmonics rather than absolute low frequency content. To me an upright bass sounds 'deeper' and richer than an electric bass despite the fact that I know that the fundamental is pretty weak off an acoustic instrument. You can get a bassy sound out of your bass as easily by rolling off the upper mids as by boosting bass. 

I like a 50Hz filter on the bass, you don't really notice any drop in bass but it cleans up the sound quite a lot, 

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Great info Phil, cheers. yes i'm the same with the EQ on my amp and previous amps. I dont boost 50hz or below

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Posted (edited)
On 25/02/2019 at 10:56, Phil Starr said:

The pickups are in completely the wrong place to pick up the fundamental, they'd need to be under the 12th fret to do that. 

I am having a very slow day so will spend some time wondering how to make this happen. I guess some sort of singlecut could provide an extra bit of wood to place a pickup in that area. 

Edited by owen

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Posted (edited)
On 05/01/2019 at 06:44, gocon said:

Just discovered this Diary, read through to page 25 and cannot find plans to make this cab.

Can anyone tell me if step by step details are available?

 

I have read all the way from post 1 looking for the drawings.

After about an hour and a half of reading (at times it felt like some ghastly clickbait trap trying to keep me digging deeper) I get to the end and find the drawing in post one isn't some speculative prototype but is the final design... >SOBS<

Anyway, thanks for all your hard work @Phil Starr !

A few questions if I may ...

I don't recall ever seeing the internal volume of the speaker and the drawing doesn't show the internal depth - I'd like to model it in WinISD for myself.


I have two 2x12 cabs with guitar/PA speakers in. I had to guess which Mackenzie speaker was in the home made one and adding two ports to it seems to have helped a bit. I wondered about fitting a 15" speaker instead of the two 12s but it's a bit small (70 litres). Interestingly WinISD insists that a Eminence Beta 15 wouldn't work as well in it as a dirt cheap 15" for £17 from CPC... and neither of them are as good as the two 12" Mackenzies.

My amp is a 150W Laney Probass of great age, which needs to be dialled to get decent volume, and with the bottem end of the EQ boosted a fair bit.

I'm wondering if using your 1x12 design would boost bottom end and would be a good complement to a 2 x 12 as I could run both for 4R.

Also, did you test your design with the Eminence Beta 12 in the end? It's about half the price of the beyma and I saw one graph that suggested it might be more efficient?

Finally, reading your early comments, a Q >5 is good for an 'old school' tone - which is what I'm after I suppose. Is is worth me looking at a the Eminence Beta 15a in a bigger cab instead?

Again, tahnks for the huge amount of work you've put into this!

Edited by Stub Mandrel

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Posted (edited)

Plans for the MK1 cab are attached. Took me ages to find them originally, so I made sure I saved it!

Hope that helps.

Basschat 1x12a.jpg

Edited by Johnny Wishbone
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18 hours ago, Stub Mandrel said:

 

I have read all the way from post 1 looking for the drawings.

After about an hour and a half of reading (at times it felt like some ghastly clickbait trap trying to keep me digging deeper) I get to the end and find the drawing in post one isn't some speculative prototype but is the final design... >SOBS<

Anyway, thanks for all your hard work @Phil Starr !

A few questions if I may ...

I don't recall ever seeing the internal volume of the speaker and the drawing doesn't show the internal depth - I'd like to model it in WinISD for myself.


I have two 2x12 cabs with guitar/PA speakers in. I had to guess which Mackenzie speaker was in the home made one and adding two ports to it seems to have helped a bit. I wondered about fitting a 15" speaker instead of the two 12s but it's a bit small (70 litres). Interestingly WinISD insists that a Eminence Beta 15 wouldn't work as well in it as a dirt cheap 15" for £17 from CPC... and neither of them are as good as the two 12" Mackenzies.

My amp is a 150W Laney Probass of great age, which needs to be dialled to get decent volume, and with the bottem end of the EQ boosted a fair bit.

I'm wondering if using your 1x12 design would boost bottom end and would be a good complement to a 2 x 12 as I could run both for 4R.

Also, did you test your design with the Eminence Beta 12 in the end? It's about half the price of the beyma and I saw one graph that suggested it might be more efficient?

Finally, reading your early comments, a Q >5 is good for an 'old school' tone - which is what I'm after I suppose. Is is worth me looking at a the Eminence Beta 15a in a bigger cab instead?

Again, tahnks for the huge amount of work you've put into this!

I'm so sorry, you poor thing, I hope it wasn't too painful :)

If you look at the dimensions the cab is a little over the 50litres I mention in the design to allow for the volume of the speaker ports and bracing. 70l is probably enough for a wide range of 15's especially as you prefer an old school bass sound. Remember 'working well' includes a number of things like cone excursion. One of the favourite (and frankly sensible) trick of cheap speakers is to keep the cone nice and light and the voice coil short so most of it is in the magnetic field. That all raises efficiency at the cost of excursion. It models well at 1W the default level for win ISD but you'd need to check at higher powers. It may be OK though of course.

I think Stevie tried the Beta 12A2, I think its going to be fine in that box and has the old school mid-range rise that I personally quite like, it won't handle the deep bass as well as the Beyma.

When looking at 'Q' you need to look at the Q of the whole system. Qts of 0.5 describes how the magnet controls the movement of the cone. Too much control damps down the bass not enough means too much. the air in the cab also damps the cone movement with more air meaning more damping, so for any speaker cab it's the combination of speaker and cab that determines the response. Qtc of the whole system should be 0.7 to get the flattest response and a speaker with qts of 0.38 is about the tipping point where cabinet design gives ends up with a flat response from a cab of reasonable size.

The Beyma will have more deep bass than many/most commercial cabs and might well fill out your bass. I can't say though whether it will give the sound you want. Combining speakers is a suck it and see thing. It might be that the 2x12 is more efficient than the Beyma and will simply dominate the quieter cab. Above the bass the two cabs will combine in an unpredictable way over the midrange and probably have a character different from either cab on it's own

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38 minutes ago, Phil Starr said:

When looking at 'Q' you need to look at the Q of the whole system. Qts of 0.5 describes how the magnet controls the movement of the cone. Too much control damps down the bass not enough means too much. the air in the cab also damps the cone movement with more air meaning more damping, so for any speaker cab it's the combination of speaker and cab that determines the response. Qtc of the whole system should be 0.7 to get the flattest response and a speaker with qts of 0.38 is about the tipping point where cabinet design gives ends up with a flat response from a cab of reasonable size. 

 

Thanks! WinICD is sucking my brain out at the moment.

In simple terms my problem is it sounds like I'm playing through guitar speakers unless I push the 40, 80 & 120 Hz sliders up to +6dB.

Extended bass will give me more headroom for normal playing and the option to turn up if I need to, as I only have a 150W (it may even be 100W the power isn't actually written on it...)

I've found these 12" MCM speakers, fairly cheap at CPC (about (£10 less than the Eminence Beta 12😞

image.png.54c04d0bc410d710b267de5efc96f7cb.png

This graph shows my current setup - Red, two MCM drivers in green, and one MCM in orange. All in the same size cabinet. This suggests a single MCM 12" in a 67 litre cabinet would work best for me.  (For comparison the Eminence Beta 12 is 3dB down on the MCM from 40 to 60Hz).

For a single driver excursion is under the red line down to 30Hz  @ 150W.

I realise that for these traces to be comparable they all need to be for the same nominal impedance.

The appeal is I could test this by fitting an 8R one instead of two 16R mackenzies and blocking the hole, if that works. If these traces are accurate my aim of being able to 'flatten' the EQ curve and get more headroom should be achieved? If it works really well, I could get another driver and permanently convert the 'twin mac'.

image.thumb.png.37d7ca81a0069951aad33bd7d0af3078.png

 

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Posted (edited)

If the specs of those speakers are reliable you've tracked down a bargain. The plots from win ISD don't quite make sense, with two 8ohm speakers in parallel you'd expect a 6dB increase in sensitivity, ie the two speakers in parallel ought to be louder across the whole plot, and of course the power handling will double. The loss of bass is to be expected, each speaker has only half the volume to operate in.

Bass extension is a mixed blessing. The cab I designed doesn't get all the bass the Beyma 212 is capable of but even so it is too bass focussed for most of the small venues I play in and I end up rolling off the bass. Without having modelled your speakers instinct tells ne they might work well in the 50l cabs I designed. It might be worth your while buiding my cab and putting one of the CPC speakers in it. If you like the sound then build a second cab. You then could potentially have most of the bass and lots of volume without the problem of trying to blend two different drivers together.

 

Edited by Phil Starr

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Things have just got more complicated!

I just won this for £131 on eBay: TRACE ELLIOT GP11 MK V Graphic Preamplifier 4x10" Bass Combo Amp.

Pickup only, but it's only about 25 miles away.

But my understanding is that the 4x10 is 8R and I can add another 8R cab...

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Posted (edited)

I think that might be loud enough for anything :)

Adding another speaker may be possible but not really necessary if you value your hearing

Edited by Phil Starr

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1 hour ago, Phil Starr said:

I think that might be loud enough for anything :)

Adding another speaker may be possible but not really necessary if you value your hearing

🤣

It's an early one, the actual power seems a matter of speculation but not huge - I've seen both 150 watts and 200 watts quoted.

I've also seen lots of comments that TE were 'conservative' in their power estimates...

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14 hours ago, Stub Mandrel said:

Things have just got more complicated!

I just won this for £131 on eBay: TRACE ELLIOT GP11 MK V Graphic Preamplifier 4x10" Bass Combo Amp.

Pickup only, but it's only about 25 miles away.

But my understanding is that the 4x10 is 8R and I can add another 8R cab...

After you've lugged that into a venue, the last thing you'll want to do is carry in an extension cab too, especially if you then have to lift the combo onto the extension. I'm sure depleted uranium is used in the construction of those things.

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1 minute ago, tauzero said:

After you've lugged that into a venue, the last thing you'll want to do is carry in an extension cab too, especially if you then have to lift the combo onto the extension. I'm sure depleted uranium is used in the construction of those things.

I think the weight is exaggerated a bit, plus they have decent handles! I might add some castors though.

It's nothing compared to the 1x18 cab I had years ago.

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8 hours ago, Stub Mandrel said:

I think the weight is exaggerated a bit, plus they have decent handles! I might add some castors though.

It's nothing compared to the 1x18 cab I had years ago.

I speak from experience. I owned one for a while. The first gig I had with it was upstairs.

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13 hours ago, tauzero said:

I speak from experience. I owned one for a while. The first gig I had with it was upstairs.

For my first band all the rehearsals were at the top of the fire escape in this google streetview clip:

image.png.8da476199ebab809e95d63f6acfe30e1.png

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